Hi KGS and welcome to Cruise-Chat.
Your kids are great ages for just about all the 7 night destinations out there. Do you want the adventure and awesome scenery of Alaska? Do you prefer a more laid back, warmer, water activity based Caribbean cruise? Do you want the historic and exciting sightseeing of a European itinerary?
Most cruise lines have great kids' facilities and programs in the summer. The question of which cruise line, ship and itinerary is best for your particular family is not easily answered by people who don't know your likes, dislikes, expectations, and budget. You'll get people giving recommendations based on how their cruises were matched to their own set of parameters.
I encourage you to speak with a cruise specialist travel agent, who can ask important questions and match you to the right vacation for your special cruise.